The ability to test a circuit completely and inexpensively is an important aspect for integrated circuit products. A loopback mechanism may be used to determine whether transmit and receive data paths are operational. In a loopback scenario, data transmitted along the transmit path is typically coupled to the receive path. The received data is compared with the transmitted data to verify the integrity of the two data paths. Provision of such functionality in integrated circuits (e.g., DRAM controller circuitry) is complex because of the timing differences between the transmit data and receive data. Existing circuitry is often complex and expensive to implement.